hideKeyboard.swift

//class need add : UITextFieldDelegate

override func viewDidLoad() {
        super.viewDidLoad()
        
        //delegate
        discountTextField.delegate = self
        sizeTextField.delegate = self
        
        //add gesture to view
        self.view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(InvCalcViewController.dismissKeyboard)))

    }
    
    
    
// dismiss keyboard function    
func dismissKeyboard(){
  sizeTextField.resignFirstResponder()
  discountTextField.resignFirstResponder()
}